Rostislav Evgenievich Alexeyev was a Russian Soviet Director & Chief of Design known for his pioneering work on hydrofoil ships and ground-effect vehicles. Alexeyev was an accomplished designer of hydrofoil ships, such as the Raketa, and became a prominent developer of ground-effect vehicles, particularly the Caspian Sea Monster and the A-90 Orlyonok.

A hydrofoil is a lifting surface, or foil, that operates in water. They are similar in appearance and purpose to aerofoils used by aeroplanes. Boats that use hydrofoil technology are also simply termed hydrofoils. As a hydrofoil craft gains speed, the hydrofoils lift the boat's hull out of the water, decreasing drag and allowing greater speeds.